Federation support checklist

[eddeee888]

• @key
  • ref should not be mapper. PR
  • Interface with @key must generate __resolveReference. PR
  • Ref types are scalar output type (?)
  • __resolveReference should return mapper if available
  • Defining advanced @keys
    • composite @key work e.g. @key(fields: "id anotherId")
    • nested @key work e.g. @key(fields: "id organization { id }")
    • multiple @key work e.g. @key(fields: "id") @key(fields: "id2")
• @interfaceObject
  • No types required
• @extends
  • No types required
• @shareable
  • No types required: this is used during composition check to say whether a field can be resolved by multiple subgraphs or used as another Graph's @key (which is implicitly shareable)
• @inaccessible
  • If an enum member is marked with inaccessible, omit it from types, otherwise there could be runtime errors
• @override
  • No types required: this is used to migrate field resolving from one subgraph to another
• @external
  • If a field is marked with @external, do not generate resolver types.
  • If a field is marked with @external, do not change other fields' signature from ParentType (using mappers) to GraphQLRecursivePick PR
  • If a type is marked with @external , generate the base type but not resolver types
  • Server Preset must not generate resolvers i.e. use resolver types instead of type interface to compare fields against mappers
• @provides
  • When @provides is used on an @external field, the field resolver type is generated
  • @provides works with nested path (Note: currently it is not generating the field resolver)
• @requires
  • Fields marked with @requires must use the normal mappers, instead of the GraphQLRecursivePick with the @key and @requires fields.
  • When there's a field marked with @requires, the __resolveReference 's ref must have a union of possible combination e.g.

type User @key(fields: "id") {
  id: ID!
  title: PersonTitle! @external
  firstName: String! @external
  lastName: String! @external
  birthYear: Int! @external

  fullName: String! @requires(fields: "firstName lastName")
  fullNameWithTitle: String! @requires(fields: "firstName lastName title")
  age: Int! @requires(fields: "birthyear")
}

Then, the type of reference is something like:

ReferenceResolver<
    Maybe<ResolversTypes["User"]>,
    { __typename: "User" } 
   & GraphQLRecursivePick<ParentType, { id: true }> // <-- from @key, must always be here
   & GraphQLRecursivePick<ParentType, { firstName?: true; lastName?: true }> <-- from @requires
   & GraphQLRecursivePick<ParentType, { firstName?: true; lastName?: true, title?: true }> <-- from @requires
   & GraphQLRecursivePick<ParentType, { birthyear?: true }> <-- from @requires
   , ContextType
  >

Note: the type for @requires needs a re-think because if fullName is in the selection set, firstName and lastName must exist in the ref together. The example above is saying there could be a scenario where firstName is there but lastName is not. We need something like AnyCombinationOf<ArrayOfRequiresOptions>

• @tag
  • No types needed
• @composeDirective
  • No types needed

---

Enterprise directives

• @authenticated
• @requiresScopes
• @policy
• @context
• @fromContext
• @cost
• @listSize

[LongLiveCHIEF]

It would be great if I could specify the federation version in the codegen.ts, and have that automatically add the extends schema @link with the correct federation version.

Is there a feature on the backlog for this?

[eddeee888]

Hello @LongLiveCHIEF
This is not planned at the moment, as this checklist is for gaps in federation types, and this sounds like a new feature.
Since this is my first time hearing it, could you help me understand how this helps users and why alternatives are not great? e.g. could the version be updated directly in the schema file/s?

[LongLiveCHIEF]

I want to take a better pass through the docs and then if I still want to discuss, I would open a new issue as a feature request.

Basically, I want to reduce the boiler plate in each schema file, and federation versions can change quite often.

There could be a banner option or something that I'm missing that would suffice for this.

[LongLiveCHIEF]

What I'm looking to do is generate the federation schema extension info in the generated schema:

Example:

extend schema
  @link(url: "https://specs.apollo.dev/federation/v2.3",
        import: ["@key", "@shareable"])

Right now, it gets stripped even when I try to put it in my base schema:

extend schema
  @link(
    url: "https://specs.apollo.dev/federation/v2.0"
    import: ["@key", "@shareable"]
  )

type Query
type Mutation

Generates:

type SomeType {}

type Mutation {
  deleteSomething(): Something!
  updateSomething(): Something!
}

type  Query {
  everything: [Something!]!
) 

I'm looking through all the docs today to see if i'm just needing to do some configuraiton to handle customizing the generated schema, but I realized I didn't really provide enough context last week, and wanted to put that in here before I forgot.

[eddeee888]

Released in https://github.com/dotansimha/graphql-code-generator/releases/tag/release-1757264511789